Runaway protection for sprayer

ABSTRACT

A method for controlling an airless sprayer ( 10 ) having an electronic control ( 12 ) with a user selectable pressure setpoint monitors the actual output pressure developed by the pump ( 14 ). When the pump output pressure drops to a selectable percentage of the setpoint, the control displays an empty message and the unit shuts off.

TECHNICAL FIELD BACKGROUND ART

[0001] Reciprocating piston pumps are commonly used as airless sprayers. Typically, the inlet of the pump is placed in a paint container such as a five gallon bucket. Traditionally, there has been a perception that such pumps, when run dry, will cause the packings and other seals to fail. Because the operator may be hundreds of feet away from the sprayer or up on a ladder, such failure can take place even with an alert operator.

DISCLOSURE OF THE INVENTION

[0002] It is therefore an object of this invention to provide an airless sprayer which is resistant to failure due to being run empty or dry.

[0003] Towards this end, an airless sprayer having an electronic control with a user selectable pressure setpoint (typically continuously variable between zero and maximum pressure) monitors the actual output pressure developed by the pump. When the output pressure drops to a selectable percentage of the setpoint (in the preferred embodiment, this percentage is 50%), the control displays an empty message and the unit shuts off. Of course the ability to use this figure is configurable so that, if desired, the pump can continue to run in spite of it not having anything to pump.

[0004] In an alternative embodiment of the instant invention, the control also looks for spraying at the full on position taking place for a user configurable length of time (40 seconds in the preferred embodiment) which might occur if a hose had burst and in some cases of the sprayer attempting to pump from an empty container. If this condition is detected, a shutoff also takes place. This mode may be in addition to the percentage mode described above.

[0005] These and other objects and advantages of the invention will appear more fully from the following description made in conjunction with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views.

BRIEF DESCRIPTION OF DRAWINGS

[0006]FIG. 1 shows a schematic diagram of the instant invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0007] Towards this end, an airless sprayer 10 having an electronic control 12 with a user selectable pressure setpoint (typically continuously variable between zero and maximum pressure) monitors the actual output pressure developed by the pump 14. When the output pressure drops to a selectable percentage of the setpoint (in the preferred embodiment, this percentage is 50%), the control displays an empty message (or provide an audio alarm) and/or the unit shuts off. Of course the ability to use this feature is configurable so that, if desired, the pump can continue to run in spite of it not having anything to pump. While the preferred embodiment of the instant invention contemplates a reciprocating piston pump, the inventive method is equally applicable to other pumps such as diaphragm or progressive cavity pumps.

[0008] In an alternative embodiment of the instant invention, the control also looks for spraying at the full on position taking place for a user configurable length of time (40 seconds in the preferred embodiment) which might occur if a hose had burst and in some cases of the sprayer attempting to pump from an empty container 16. If this condition is detected, a shutoff also takes place. This mode may be in addition to the percentage mode described above.

[0009] It is contemplated that various changes and modifications may be made to the method without departing from the spirit and scope of the invention as defined by the following claims. 

1. A method for protecting a pump having a control with a user selectable pressure setpoint comprising the steps of: selecting a setpoint; monitoring the actual output pressure developed by said pump; determining when said pump output pressure drops to a predetermined percentage of said setpoint; and providing a means for indicating an error condition.
 2. The method of claim 1 wherein said means for indicating an error condition comprises a visual indicator.
 3. The method of claim 1 wherein said means for indicating an error condition comprises a audio indicator.
 4. The method of claim 1 wherein said means for indicating an error condition comprises disabling the unit from spraying. 